Knife sharpener



FIG. 1 is a perspective view of a knife sharpener showing my new design from above;

FIG. 2 is a left side view thereof;

FIG. 3 is a right side view thereof;

FIG. 4 is a top view thereof;

FIG. 5 is a bottom view thereof;

FIG. 6 is a front view thereof;

FIG. 7 is a rear view thereof;

FIG. 8 is an additional perspective view thereof from below; and,

FIG. 9 is a right side view of the knife sharpener, shown removably attached to a knife handle in broken line for completeness of illustration.

The broken lines shown in the drawings are for illustrative purposes only and form no part of the claimed design. 

CLAIM The ornamental design for a knife sharpener, as shown and described. 